1. Field of the Invention
The invention is related to light weight aircraft. More particularly, the invention is related to a system and method for eliminating, or substantially reducing, and controlling the twist of sailwings on lightweight aircraft.
2. Background Art
Previous attempts at using sailboat type membrane sails for aircraft wings have had major problems with controlling the twist of the wing. A large amount of spanwise tension is needed in the sail, particularly at the trailing edge to control the twist of the airfoil under load. The wing spar (mast) is well ahead of the centroid of the aerodynamic forces, and this results in a significant upload at the back of the sail. Normally this load is reacted out by trailing edge tension, resulting in a type of catenary curve. The higher the tension, the flatter this curve, but this gives a large aft bending moment in the spar. With tolerable spar loads, the wing might have over 10 degrees twist, which can give poor induced drag, as compared to a more normal wing.
Thus, a need exists for a wing structure on a light weight aircraft that can reduce the twist on the sailwing, thereby reducing induced drag, and increasing the available wing lift.